Unmanned lighter-than-air ballooncraft have been used for many years to perform tasks such as near space research, and meteorological measurements. Such ballooncraft have even carried payloads with instrumentation that sometimes includes radio transmission capabilities.
Until recently, all communications satellites were located on one orbit called the geosynchronous arc, which is located 22,300 miles above the Earth's equator. Since international treaties required satellites to be spaced two degrees apart, there were only 180 sites on geosynchronous orbit. An optimally-designed three-stage chemical rocket typically must be 94% propellant at launch to reach geosynchronous orbit, which, after allocating about 5.6% of the weight for the rocket, only leaves about 0.4% of the initial launch weight for the satellite. To put this in perspective, a typical 3,000 lb. automobile with the same performance would only be able to carry one 200 lb. person, would need an 8,400-gallon fuel tank, and would be junked after one trip! Finally, although the NASA space shuttle can service a few very low orbit satellites at great expense, most satellites cannot be serviced or upgraded after being launched.
Currently, since there are a limited number of sites on the geosynchronous orbit, geosynchronous satellites are growing in size and performance, now being able to broadcast television signals directly to homes. Recently, additional satellite networks have been deployed that do not require a geosynchronous orbit. All of these new networks have launched smaller communication satellites into much lower orbits where there are an unlimited number of sites. Because the satellites required for a network are more numerous and because the satellites are smaller, up to 8 satellites per rocket have been launched. Although satellites have become smaller and more numerous, there are still no “personal satellites” and no mass producers of consumer products in the satellite industry today. It might be estimated that a network of microsatellites in low Earth orbit and ground equipment to accommodate the tracking, transmission, reception, signal handoff among the plurality of microsatellites and necessary system network for a voice system would cost at least $3 billion to deploy. Within four years of deploying a system, each one of five million subscribers might be expected to invest as much as $3,000 in the equipment, which results in a total combined investment by the users in the new equipment of about $15 billion. The cost of deploying a smaller system of low Earth orbit advanced messaging satellites might be estimated at about $475 million. Such a system might be expected to serve two to three million subscribers, each with user equipment costing $300-$1,000. Thus, the total investments by the users for their equipment may be at least $600 million.
There is currently an industry involving radiosondes for purposes of gathering weather information. Radiosondes are the instrument packages launched on weather balloons to gather weather data. Radiosondes are launched from a network of sites around the world at noon and at midnight Greenwich Mean Time each day. The weather service radiosondes collect temperature, humidity, pressure and wind data as they rise from the surface of the Earth to approximately 100,000 feet during a two-hour flight. This data is then input in atmospheric models that are run on supercomputers. The information gathered from the network of ascending radiosondes is critical in predicting the weather. Most countries of the world are bound by treaty to launch radiosondes from designated sites and to share the data with other countries. Currently there are about 800,000 radiosondes launched each year throughout the world. This number represents the 997 global weather stations launching two radiosondes per day, 365 days per year (727,000) plus a small number of radiosondes launched for research purposes. About 18% of radiosondes are recovered, reconditioned and reclaimed, resulting in new production of about 650,000 weather-gathering radiosondes per year.
The location systems currently used to track weather balloons are either being deactivated (Omega, beginning before the year 2000, and Loran-C, shortly after the year 2000) or are so old that the operation and maintenance is becoming prohibitively expensive (radars and radiotheodolites).
Changes in radiosonde systems are usually very slow, since meteorologists study climatic trends by comparing data collected over decades. Thus, they are very leery of any changes that may introduce new biases into data as it is collected. This is evident from the fact that major users, like the U.S. National Weather Services (NWS) still use analogue radiosondes tracked by radiotheodolites when digital, navaid sondes have been around for many years. Tightening of governmental budgets has made some users unable to pay for new technology required. There presently is a push in the sonde marketplace to convert to using the Global Positioning System (GPS) for wind tracking on radiosondes. From 1995 to 1998, the NWS tried and failed to get the U.S. Congress to fund a program to develop a GPS tracking system for the U.S. Observation Network. This inability to obtain the necessary newer technology to replace old and unsupportable radiosonde infrastructure is occurring simultaneously with the rapid reallocation of the radiosonde's RF spectrum to commercial uses. Radiosondes have traditionally transmitted at 400 MHZ for navaid sondes and 1680 MHZ for radiotheodolite sondes. The 400 MHZ band is being auctioned off by the Federal Communications Commission (FCC) in the United States for simultaneous use by commercial services. Thus, interference is increasing and sondes may be forced to use to narrower bandwidths with digital downlinks instead of the wide bands with analogue downlinks still in common use.
Very large and expensive NASA balloons have been individually launched and maintained at a floating altitude for extended periods of time. These balloons carry hundreds of pounds of equipment and cost tens of thousands of dollars each. The single balloons do not have the capability of line-of-sight coverage with entire geographic areas.
Personal communications services (PCS) are a new category of digital services that the FCC started auctioning spectrum for in 1994. PCS is split into two categories: broadband and narrow band PCS. The broadband category is primarily for voices services and PCS broadband phones now compete with traditional cellular phones. The narrow band category is for advanced messaging, which is essentially two-way paging. The paging industry sees advanced messaging as being the mobile extension of one's e-mail account, just as a cellular phone has been the mobile extension of one's desktop phone. Nationwide narrow band PCS (NPCS) was the first spectrum ever auctioned by the FCC. About 30 regional and nationwide NPCS licenses have been auctioned and sold to private commercial ventures. The fact that the spectrum was auctioned is significant in that there are fewer restrictions on the use of this spectrum than on the use of traditional spectrum licensed from the FCC. Before auctions, the FCC granted spectrum on a piecemeal basis, and companies had to prove that they were using the airwaves for the “public good.” Usually there was very specific federal regulation on how the frequency could be used. Since companies paid for their PCS licenses, they essentially owned the spectrum. The FCC imposed only minimal regulations required to prevent systems from interfering with other carriers' and other countries' systems. Additionally, the FCC and Industry Canada reached what is known as a Terrestrial Radio Communication Agreement and Arrangement in which Canada allocated the same frequencies for NPCS with the same channel structure as the auctioned spectrum for the NPCS in the United States. This made cross-border NPCS possible and in 1996, at least one paging system company was granted an NPCS license in Canada to operate on the same frequencies as its U.S. licensee. Mexico also has specified the same channel spacing as used in the United States.
One of the goals of the FCC is to encourage providing radio frequency (RF) communications services to consumers in rural areas at an affordable price. This market has been largely ignored by the larger communications companies because of the diminishing return on investment in providing wireless communications to sparsely populated areas. These wireless services include paging, advanced messaging, telemetry, voice, etc. Although both voice and messaging services are available to rural areas using satellite systems, the costs are generally in the thousands of dollars per unit and well out of reach of most consumers. In addition satellite systems have problems providing services in urban areas because they lack the signal strength necessary for providing building penetration.